Method and apparatus for making an integral rivet connection



July 19, 1955 o. E. SCHMIDT 2,713,197

METHOD AND APPARATUS FOR MAKING AN INTEGRAL RIVET CONNECTION Filed Jan. 23, 1952 INVENTOR OEEmar E. Schmidt A TTORNE Y United States Patent 1 2,713,197 METHQD AND APPARATUS FOR MAKING AN INTEGRAL RIVET tlGNNECTION Ottrnar E. Schmidt, Grosse Pointe Woods, Mich, assignor to The Budd Company, Philadelphia, Pa., :1 corporation of Pennsylvania Application January 23, 1952, Serial No. 267,786 16 Claims. (Cl. 29-432) This invention relates to an integral rivet connection, particularly to a wheel disk and rim connection, and to the method and apparatus for making it, and has for an object the provision of improvements in this art.

The present invention is a continuation-in-part and an improvement upon that disclosed in my copending application Serial No. 155,867, filed April 14, 1950.

It is a common practice in current wheel manufacture to form wheel disks with an axially extending peripheral flange, then force-fit this within a wheel rim, and then to rivet the flange to the rim.

In the application referred to, a new method of securing the flange and rim together is disclosed. This comprises the steps of forming an integral rivet-like projection on one of the metal thicknesses within a hole in the other metal thickness and upsetting the end of the projection to rivet the parts together. This connection, which may be referred to as an integral rivet connection, avoids the use of separate rivets and separate punching and rivet-inserting operations, with consequent cost savings, and, moreover, forms a stronger connection.

It is an object of the present invention to improve the integral rivet connection.

Another object is to provide more consistently good connections.

Another object is to provide improved means for forming the connection.

The above and other objects will be apparent from the following description of an exemplary embodiment, reference being made to the accompanying drawings, wherein:

Fig. 1 is a trans-axial section through a finished wheel disk and rim assembly made according to the present invention, the riveting tools being indicated in broken lines;

Fig. 2 is an enlarged partial axial section taken on the line 22 of Fig. 1 and showing the tools in full lines;

Fig. 3 is a further enlarged section, similar to Fig. 2, showing the beginning of the first operation which in one action forms a hollow rivet-like projection on one part, forms a hole in the other part, and forces the projection through the hole;

Fig. 4 is a section, similar to Fig. 3, showing a further stage of the first step;

Fig. 5 is a section, similar to Figs. 3 and 4, showing the final stage of the first step;

Fig. 6 is a similar section, showing the beginning of the second step of the operation; and

Fig. 7 is a similar view, showing the completion of the second step.

The invention comprises a process by which the connection is formed in two steps. In the first step, as shown in Figs. 3, 4 and 5, a hollow round-ended projection is formed on one thickness and as it is being formed it forces a slug out of a juxtaposed thickness and enters the hole thus formed. In the second step the end of the hollow projection is upset, a shown in Figs. 6 and 7, to rivet the thicknesses together.

The improvement provided by the present invention is to form an annular depression around the outer end of the hole to cause the metal at the end of the hollow projection to start turning outward and to cause it to extend uniformly and concentrically around the entire periphery of the head formed on the projection.

As indicated in Fig. l, a plurality of tools or die sets "ice form all of the connections for the wheel simultaneously. Since the disk flange is initially pressed tightly within the rim and since the first step in the process leaves projections within holes at spaced intevals throughout the entire circumference of the wheel, the parts are held securely together in readiness for the next step in the process in which the projections are upset or riveted in the holes.

As shown in Fig. 3, the juxtaposed tightly interfitted peripheral axial flange 16 of a wheel disk D and the interior axially extending portion 11 of a rim R, are first subjected to the action of a die set which includes a male member or punch 12 and a female member or button 13.

The punch has a rounded projecting end 12:: which engages the surface of the adjacent thickness of metal at the central axis of the dies. The button 13 is formed with a relatively narrow interior annular end projection 13a which, as shown in Fig. 4, at an early stage, presses into the surface of the metal thickness which is adjacent to it and forms an annular depression 11a therein. This action not only forms a cut to start the formation of a slug 111), Fig. 5, which is punched out of the thickness 10 to form a hole 11c therein; but also assists in the later endupsetting or riveting action on the closed-end hollow projection 16a which (Fig. 4) is formed in the thickness 11 in the first step of the process.

In this first step, the slug 11b is forced completely out of the thickness 11 and into the tubular hole of the button die 13. The hollow projection 10a of the thickness 19' has its rounded outer end 10(11 forced through the hole until the sides of the projection 1M2, which approach the cylindrical form, are almost in contact with the inner sharp edge of the annular projection 13a of the die button 13. The metal, however, is not cut because the projecting end 12a is suficiently smaller than the hole in the button to allow a metal thickness to be disposed therebetween and because the shoulders 12b of the punch bring up against the fiat part of the lower thickness.

The hole 110 formed in the thickness 11 is rounded at its inner end 1101, the end adjacent the thickness 11), and is generally conical of decreasing diameter outward at 1102 to a relatively sharp edge 11c3 at the inner edge of the annular portion 13a of the button die. This sharp edge, which is somewhat hardened in the forming operation, fits tightly around the generally cylindrical portion of the projection 19a and this relationship greatly aids the subsequent head-forming operation.

In the subsequent step the heads of all the rivet-like projections of the Wheel are formed simultaneously. Fig. 1 indicates the general disposition of die sets and Fig. 2 shows the arragement of one die set and some of the adjacent press parts for holding the disk and rim in proper position and minimizing deformation of parts in the operation. The function of these parts is obvious from the illustration and need not be described.

The finishing die set is shown separately in Figs. 6 and 7 and comprises a male die member or punch 15 and a mating die member or button 16. The button 16 is shown to be generally fiat on its operating end.

The male die part or punch 15 has a flat end 15a and a concave curved shoulder 1522 which joins the flat end 15a in a pronounced rounded corner 150. This shape is' vey effective in firmly gripping the metal at the start of the heading operation, as shown in Fig. 6, the annular corner 15c pressing the metal of the projection hard against the sharp edge 1103 of the hole to hold it against backflow during the heading action. As is well-known, metal acts like a viscous body and tends to flow around curved edges, so advantage has here been taken of this knowledge and the tight initial clamping between relatively sharp edges causes the maximum amount of metal in the end 10a1 of the hollow projection to be retained beyond the outer end of the hole in the outer metal thickness 11 to form the head 1Ga3.

During the final stages of the heading action, the head 10a3, in forming, causes the sharp edge 11c3 to disappear and an outflaring conical portion 1104 to be formed in the hole, but a pronounced constriction 1105 is left in the hole which strongly holds the conical head of the projection.

Also, and most importantly, it is found that the heads 7 are all uniformly concentric and smooth about the axis of the projection and hole and do not tend to have a Scalloped edge or an eccentric arrangement, as was the case at times before. In the present preferred form the ends of the heads are substantially flush with the outer surface of the metal sheet, that is: the heads lie entirely within the holes; This relationship is produced by having the projections pushedthrough the holes in the first operation until approximately the thickness of the metal at the small end of the projection stands above the outer sur-- face of the other thickness, as shown in Figs. 5 and 6. Then, when the head is formed and presses out the sides of the hole to form the outer reversely enlarging portion 7 11c4, the end of the head is brought flush with the outer surface of the outer metal sheet, as shown in Fig. 7.

Tests have shown that the heads are uniformly wellformed and strong, and wheels made according to the present invention give much better service than wheels made with rivets.

It is normally more convenient to form the projection on the disk flange and the hole inthe rim, and this is the form which is illustrated, but, if more convenient, the projections could be made in the rim and the holes'in the disk flange. If the projections are formed in the rim, it may be desirable to fill the depressions which are left in order to provide a smooth surface from the inner tube of the tire.

While one embodiment of the invention has been illustrated and described, it is to be understood that there may be other embodiments within the general scope of the invention.

What is claimed is:

l. The method of securingtogether two face-engaging metal sheets which comprises, forming in a front sheet a round-ended rearwardly extending hollow, circumferential- 1y continuous projection while supporting the back surface of the rear sheet in an annular zone around the longitudinal axis of the projection, the inside diameter of said back-supported annular zone being enough greater than the diameter of the hollow interior portion of the projectionto allow the projection to enter without shear in its sidewalls, continuing the action to' force out a slug and form a hole within the annular back-supported zone of the rear sheet and to force the rounded end and unsheared sides of the hollow projection through the hole which the projection has formed until the rounded end of the projection extends beyond the rear end of the hole, the thickness of the sheets being such and the action being continued to such an extent that the interior hollow portion of the projection is disposed at least in part within the hole.

2. The method of securing together two face-engaging metal sheets which comprises, forming in a front sheet a round-ended rearwardly extending hollow circumferentially continuous projection while supporting the back surface of the rear sheet in an annular zone around the longitudinal axis of the projection, the inside diameter of said back-supported annular zone being enoughgreater than the diameter of the hollow interior portion of the projection to' allow the projection to enter without shear in its sidewalls, continuing the action to force out a slug and from a hole within the annular back-supported zone of the rear sheet and to force the rounded end and unsheared sides of the hollow projection through the hole which the projection has formed until the rounded end the thickness of the sheets being such and the action being continued to such an extent that the interior hollow portion of the projection is disposed at least in part within the hole, and subsequently, while keeping the projection in position in the hole which it has formed, holding the side walls of the projection outward tightly against the sides of the hole to minimize back flow of metal in the sides of the projection while leaving the interior of the rounded end of the projection unsupported, and upsetting the rounded end of the projection to form a head on the projection to secure the sheets together.

3. The method of securing together two face-engaging metal sheets'which comprises, forming in a front sheet a round-ended conical-sided rearwardly extending hollow circumferentially continuous projection while supporting the back surface of the rear sheet in an annular zone around the longitudinal axis of the projection, the inside diameter of said back-supported annular zone being enough greater than the diameter of the hollow interior portion of the projection to allow the projection to enter without shear in its sidewalls, continuing the action to force out a slug and form a hole within the annular backsupported zone of the rear sheet and to force the rounded end and unsheared sides of the hollow projection through the hole and the conical sides of the projection have formed an embracing conical portion in the hole.

4. The method of securing together two face-engaging metal sheets which comprises, forming in a front sheet a round-ended conical-sided rearwardly extending hollow circumferentially continuous projection while supporting the back surface of the rear sheet in an annular zone around the longitudinal axis of the projection, the inside diameter of said back-supported annular zone being enough greater than the diameter of the hollow interior portion of the projection to allow the projection to enter without shear in its sidewalls, continuing the action to force out a slug and form a hole within the annular backsupported zone of the rear sheet and to force the rounded end and unsheared sides of the hollow projection through the hole which the projection has formed until the rounded end of the projection extends beyond the rear end of the hole and the conical sides of the projection have formed an embracing conical portion in the hole, and subsequently, while keeping theprojection in position in the hole which it has formed, holding the conical portion of the projection tightly in the conical portion of the hole while leaving the rounded outer end of the projection unsupported, and upsetting the end of the projection while thus held to form a head on the projection to hold the sheets together. 7

5. The method of securing together two face-engaging metal sheets which comprises, forming in a front sheet a round-ended conical-sided rearwardly extending circumferentially continuous projection while supporting the back surface of the rear sheet in an innernarrow annular zone of primary support and in a wider outer annular zone of secondary support, the inside diameter of the inner backsupported annular zone being enough greater than the hollow interior portion of the projection to allow the projection to enter without shear in its sidewalls, continuing the action to force out a slug and form a hole within the annular back-supported zone of the rear sheet, to form a narrow countersunk depression around the rear end of the hole with a sharp inner edge at the bottom of the depression, and to force the rounded end and the unsheared sides of the hollow projection through the hole which the projection has formed until the rounded end of the projection extends beyond the rear end of the hole and the conical sides of the projection have formed an embracing conical portion in the hole.

6. The method of securing together two face-engaging metal sheets which comprises, forming in a front sheet a round-ended conical sided rearwardly extending circumferentially continuous projection while supporting the back surface of the rear sheet in an inner narrow annular zone of primary support and in a wider outer annular zone of secondary support, the inside diameter of the inner back-supported annular Zone being enough greater than the hollow interior portion of the projection to allow the projection to enter without shear in its sidewalls, continuing the action to force out a slug and form a hole within the annular back-supported zone of the rear sheet. to form a narrow countersunk depression around the rear end of the hole with a sharp inner edge at the bottom of the depression, and to force the rounded end and the unsheared sides of the hollow projection through the hole which the projection has formed until the rounded end of the projection extends beyond the rear end of the hole and the conical sides of the projection have formed an embracing conical portion in the hole, and subsequently, while keeping the projection in position in the hole it has formed, holding the conical portion of the projection tightly against the sharp edge of the hole below the countersunk rear depression while leaving the rounded outer end of the projection unsupported and upsetting the end of the projection while thus held to fill the countersunk depression at the rear end of the hole and form a hole on the projection to hold the sheets together.

7. The method of securing together two face-engaging metal sheets, which comprises, providing an assembly in which a hollow base-flaring round-ended projection on one sheet is wedged tightly in a base-flaring hole in the other sheet with the rounded end only of the projection extending beyond the end of the hole, backing the interior of the projection to wedge its sides tightly in the hole to minimize back-flow of metal while leaving the rounded end unsupported, and upsetting the rounded end to form a flaring head to hold the sheets together.

8. The method of securing together two face-engaging metal sheets, which comprises, providing an assembly in which a hollow round-ended conical-sided, base-flaring projection on one sheet is wedged tightly in a form-fitting hole in another thickness, the hole having a narrow countersunk depression in its outer end and a sharp edge at the bottom of the depression, with the rounded end of the projection extending beyond the outer end of the hole, backing the interior of the projection to wedge the sides tightly against the sides of the hole and the sharp edge to minimize back-flow of metal while leaving the rounded end unsupported, and upsetting the rounded end to fill the countersunk depression and form a head on the projection to hold the sheets together.

9. Apparatus for forming an integral rivet connection between two sheet thicknesses, comprising a rivet and hole forming die set which includes a button die having a tubular hole along its axis and a narrow shallow annular projection immediately surrounding the hole and wide flat surface surrounding the annular projection, and a punch having a central projection of considerably smaller diameter adjacent the end than the diameter of the hole in the button die, the end of the projection being rounded, said punch behind the end of the projection having extended concave shoulders extending outwardly to the sides of the punch to a greater diameter than the outer diameter of the shallow annular projection on the button die, the punch and button die when brought together forming a hollow closed-ended projection on on: sheet thickness on the punch side which forces a slug out of the other thickness and forces the hollow projection through the hole formed by punching out the slug.

10. Apparatus for forming an integral rivet connection, comprising a heading die set for a construction in which a conical tubular closed-ended projection on one thickness of metal extends through a hole in a juxtaposed thickness of metal with the sides of the tubular projection engaging a sharp rib at the lower end of a narrow shallow annular depression around the end of the hole,

said heading die set comprising a generally flat-ended button die for engaging the outer end of the tubular projection and a punch having a reduced portion fitting the sides of the tubular portion to the sharp rib, the punch also having extensive concave shoulders behind the reduced end portion which extend to the sides of the punch, the punch and button die when forced together holding the body of the projection against retrograde movement through the hole and forming an outwardly enlarging conical flanged head on the closed end of the tubular projection, at the same time forcing the rib radially outward and forming an outer conical portion in the hole for the head.

11. The method as set forth in claim 1, further characterized by the fact that a plurality of such connections are made in the same parts simultaneously, so that the several projections will hold the parts accurately and securely together and prevent creep which might displace or put undue strain on one or another of the connections.

12. The method as set forth in claim 2, further characteriz d by the fact that in the first said operation there are simultaneously formed in the same parts a plurality of projections and projection-receiving holes and that in the said subsequent operation all of the projections are headed, so that the several projections will hold the parts accurately and securely together and prevent creep which might displace or put undue strain on one or another of the connections.

13. The method as set forth in claim 1, further characterized by the fact that a plurality of such connections are made at spaced points around a circumferentially complete assembly of overlapping sheet thicknesses, so that the several projections will hold the parts accurately and securely together and prevent creep which might displace or put undue strain on one or another of the connections.

14. The method as set forth in claim 2, further characterized by the fact that a plurality of such projections and holes are formed in the first said operation at spaced points around a circumferentially complete assembly of overlapping sheet thicknesses and that in the said subsequent operation all of the projections are headed, so that the several projections will hold the parts accurately and securely together and prevent creep which might displace or put undue strain on one or another of the connections.

15. The method as set forth in claim 1, further characterized by the fact that said projections and holes are formed at a plurality of spaced points around the periphcry of a circumferentially complete structure and that the projections have their closed ends directed inward so that the outer sheet thickness is imperforate.

16. The method as set forth in claim 1, further characterized by the fact that said projections and holes are formed at a plurality of spaced points around the periphery of a circumferentially complete structure and that the projections have their closed ends directed outward so that the inner sheet thickness is imperforate.

References Cited in the file of this patent UNITED STATES PATENTS 11,413 Carhart Aug. 1, 1854 521,825 Shipe June 26, 1894 820,586 Marshall May 15, 1906 875,263 Hertwig Dec. 31, 1907 1,446,095 Karaus Feb. 20, 1923 1,571,673 Jayne Feb. 2, 1926 1,784,256 Stout Dec. 9, 1930 2,220,135 Wardell Nov. 5, 1940 2,254,558 Williams Sept. 2, 1941 2,321,755 Kost June 15, 1943 FOREIGN PATENTS 361,353 Germany Oct. 13, 1922 373,881 Germany Apr. 17, 1923 590,720 Great Britain July 25, 1947 

